jeffwhitfield
Well-known member
Ok, so...I have a handful of 12AX7 tubes I got so I could try out different ones in the Maxon RTD800 tube drive pedal I got. None of them worked as well as the default EHX 12AX7 so I held onto them for a later day. Figured that one day I could put together a BK Butler clone and try out different tubes. Well...lo and behold, Madbeans made my wish come true. Hoped on it and got an Archibald to play with! 
The build went pretty smooth. Although I did managed to screw up the orientation of the PCB board for the tube. Got it upside down so I had to completely destroy the angled header to get it off without damaging the PCB. Had to order some more headers so a bit of a wait on that. Once I got the new headers, the rest went pretty smooth. Everything fired up and appeared to be working just fine.
Once I got the components installed and calibrated the voltage, I popped in one of the three tubes I got: EHX 7025, Sovtek 12AX7LPS, JJ ECC83JJ. I started with the Sovtek since I knew that one worked pretty well in the Maxon. At first, it just spurted out things in a rather gated fashion. Tried out the other tubes with no luck. Turned out to be the fact that the optional buffer needed to be on. Seems this circuit is a bit finicky about the impedance. Buffer helps with that. With the buffer on, everything worked just fine.
Out of the three tubes, the JJ seemed to work the best. It provided the best range of gain without it sounding too shrill. The Sovtek worked well but the upper part of the gain just seemed a bit much and too crunchy. The EHX 7025 didn't work at all. It just sputtered out no matter what I did. I also pulled out the standard EHX 12AX7 from my Maxon and that one worked pretty damn well. In fact, I ordered another one for the Archibald. Figure it'll be between it and the JJ. I have a feeling that the EHX will win out though. Seems it's the most balanced of all the tubes.
Design-wise, I kept it super simple and mimicked the original BK Butler a bit. Question is: How does it compare to my Maxon pedal? Will find out soon enough.
The build went pretty smooth. Although I did managed to screw up the orientation of the PCB board for the tube. Got it upside down so I had to completely destroy the angled header to get it off without damaging the PCB. Had to order some more headers so a bit of a wait on that. Once I got the new headers, the rest went pretty smooth. Everything fired up and appeared to be working just fine.
Once I got the components installed and calibrated the voltage, I popped in one of the three tubes I got: EHX 7025, Sovtek 12AX7LPS, JJ ECC83JJ. I started with the Sovtek since I knew that one worked pretty well in the Maxon. At first, it just spurted out things in a rather gated fashion. Tried out the other tubes with no luck. Turned out to be the fact that the optional buffer needed to be on. Seems this circuit is a bit finicky about the impedance. Buffer helps with that. With the buffer on, everything worked just fine.
Out of the three tubes, the JJ seemed to work the best. It provided the best range of gain without it sounding too shrill. The Sovtek worked well but the upper part of the gain just seemed a bit much and too crunchy. The EHX 7025 didn't work at all. It just sputtered out no matter what I did. I also pulled out the standard EHX 12AX7 from my Maxon and that one worked pretty damn well. In fact, I ordered another one for the Archibald. Figure it'll be between it and the JJ. I have a feeling that the EHX will win out though. Seems it's the most balanced of all the tubes.
Design-wise, I kept it super simple and mimicked the original BK Butler a bit. Question is: How does it compare to my Maxon pedal? Will find out soon enough.
